Method of manufacturing laminated core

ABSTRACT

In a method of manufacturing a laminated core, a laminated core body  14  including magnet insertion holes  12  and  13  with magnet pieces  15  inserted therein is placed between a molding (upper) die  10  and a retaining (lower) die  11 , and a molding resin  19  is filled from resin reservoir portions (pots)  16  to fix the pieces  15  in the holes  12  and  13 . Between the die  10  and the body  14 , a guide member  18  is placed, which includes resin passages  31  provided from the portions  16  to the holes  12  and  13  and gates  30  connecting to the holes  12  and  13  on downstream sides of the passages  31 . The method can reduce lead time of a production line without replacing the molding dies for different laminated rotor cores and thus without preparing different types of molding dies.

TECHNICAL FIELD

The present invention relates to a method of manufacturing a laminatedcore for a motor, the laminated core with a magnet piece resin-sealed ineach of a plurality of magnet insertion holes axially-penetratingtherethrough.

BACKGROUND ART

Conventionally, as described in Patent Literature 1, a magnet moldingmethod A is known, in which a plurality of magnet insertion holes areprovided for a laminated core body of a laminated rotor core, and amagnet piece is inserted and fixed in each of the magnet insertionholes. In this method, as shown in FIG. 8, magnet pieces 72 are insertedin a plurality of magnet insertion holes 71 provided in aradially-outward region of a laminated rotor core 70. After thelaminated rotor core 70 is heated to a certain temperature, a moldingresin 75 is injected from an upper die 73 (or a lower die 74) into themagnet insertion holes 71. By curing the molding resin 75, the magnetpieces 72 are fixed to a laminated core body 76. A reference numeral 77denotes a carrier fixture, a reference numeral 78 denotes an upperfixing plate, a reference numeral 79 denotes a lower fixing plate, areference numeral 80 denotes a guide post, and a reference numeral 81denotes a plunger.

However, in the method described in Patent Literature 1, the moldingresin 75 remains on a resin passage portion of a surface of thelaminated rotor core and a gate portion which connects to the magnetinsertion hole 71. Therefore, after the molding resin is filled, aprocess to remove the resin remained on the surface is needed. Thus,Patent Literature 2 discloses a magnet molding method B wherein a dummyplate is used.

In the magnet molding method B, as shown in FIG. 9, a dummy plate 82 isdisposed on a top surface of a laminated core body 76. The molding resin75 is injected through a gate 83, a resin injection hole, provided onthe dummy plate 82. Thus, the injected molding resin 75 adheres to andremains on a surface of the dummy plate 82, not on the top surface ofthe laminated core body 76. Therefore, by removing the dummy plate 82from the laminated core body 76, the residual molding resin is alsoremoved at the same time. A reference numeral 84 denotes a resin passageprovided in the upper die 73.

CITATION LIST Patent Literature

-   [Patent Literature 1] Japanese Patent No. 3786946-   [Patent Literature 2] Japanese Patent No. 4414417

SUMMARY OF INVENTION Technical Problem

However, in the magnet molding methods described in Patent Literature 1and 2, it is necessary to change a shape of a molding die (upper die orlower die) including a resin reservoir portion and a dummy plateaccording to a given laminated core body whenever the positions or thenumbers of the magnet insertion holes of the laminated core body arechanged. Therefore, if the molding die is prepared according to a typeof a laminated rotor core, manufacturing cost increases. Moreover, in aproduction line, the molding die must be replaced whenever the type ofthe laminated rotor core is changed. Accordingly, including adjustmentafter replacing the molding die, it takes several dozens of minutes toseveral hours to restart production, resulting in a hindrance to areduction of production time.

The present invention has been made in view of the above circumstances,and it is an object of the present invention to provide a method ofmanufacturing a laminated core, which can reduce lead time of theproduction line without changing the molding die for each differentlaminated rotor core and thus without preparing another type of moldingdevice.

Solution to Problem

To accomplish the above object, the present invention provides a methodof manufacturing a laminated core, the laminated core formed by placinga laminated core body having magnet pieces inserted in magnet insertionholes thereof between a molding die and a retaining die, filling amolding resin from resin reservoir portions of the molding die to themagnet insertion holes, and thereby fixing the magnet pieces in themagnet insertion holes, the method including: placing a guide memberbetween the molding die and the laminated core body, the guide memberincluding: a) groove-type resin passages provided from the resinreservoir portions to the magnet insertion holes; and b) gates ondownstream sides of the resin passages, the gates connected to themagnet insertion holes.

Here, if the laminated core body stands vertically, the molding die isdisposed at a top or a bottom of the laminated core body. The guideportion is correspondingly disposed at the top or the bottom of thelaminated core body.

In the method of manufacturing the laminated core according to thepresent invention, it is preferable that the guide member be made of oneflat plate (e.g., stainless steel plate or steel plate), the resinpassage include a groove opened to the molding die, and the gate be athrough-hole provided at an end of the resin passage.

Also, in the method of manufacturing the laminated core according to thepresent invention, it is preferable that the guide member include atleast two flat plates (e.g, stainless steel plate or steel plate), andthe resin passage be formed by penetrating through one of the flatplates adjoining the molding die. It is further preferable that the gatebe formed in another flat plate adjoining the laminated core body, andbe a through-hole connected to the downstream side of the resin passage.

In the method of manufacturing the laminated core according to thepresent invention, it is preferable that when viewed in plan, the gatebe smaller than the magnet insertion hole, and overlap with the magnetinsertion hole on a radially-inward region thereof. Here, the term “whenviewed in plan” means to look at the laminated core body in an axialdirection. Accordingly, the resin at where the magnet insertion hole andthe gate abut each other can be broken easily, and the unnecessary resincan be removed easily.

In the method of manufacturing the laminated core according to thepresent invention, it is preferable that the molding die include aplurality of the resin reservoir portions, from which the molding resinbe supplied to a plurality of groups of the magnet insertion holes(including one or a plurality of the magnet insertion holes) formed inthe laminated core body.

In addition, in the method of manufacturing the laminated core accordingto the present invention, it is preferable that a diameter of the guidemember be larger than a diameter of the laminated core body.Accordingly, the guide member can be easily removed after resin-sealing.

Advantageous Effects of Invention

The method of manufacturing a laminated core according to the presentinvention has the following effects:

(1) In a production line in operation, even if a type of the product tobe molded (i.e., laminated core) is changed during the operation,molding is enabled only by setting a guide member corresponding to theproduct without replacing a molding die, it is thus possible tomanufacture the product continuously without stopping the productionline.(2) Thus, for a specific product type, it is only necessary to replacethe guide member as the type of the product is changed, and it istherefore possible to reduce lead time.(3) It is further possible to significantly reduce costs for dies andproduction because it is not necessary to manufacture a molding die foreach product type.

Specifically, by using at least two flat plates for the guide member, itis possible to prevent the resin from remaining on a surface of theproduct. Further, by separating the at least two flat plates, theresidual resin can be removed very easily.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram showing a method of manufacturing alaminated core according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a carrier fixture used in the method.

FIG. 3(A) is a plan view showing a guide member used in the method, andFIG. 3(B) is a plan view showing a laminated core manufactured by themethod.

FIG. 4(A) is a plan view showing a guide member used in a method ofmanufacturing a laminated core according to a second embodiment of thepresent invention, and FIG. 4(B) is a plan view showing a laminated coremanufactured by the method.

FIG. 5 is an explanatory diagram showing a method of manufacturing alaminated core according to a third embodiment of the present invention.

FIGS. 6(A) and 6(B) are explanatory diagrams showing a guide member usedin the method, and FIG. 6(C) is a plan view showing a laminated coremanufactured by the method.

FIGS. 7(A) and 7(B) are plan views showing a guide member used in amethod of manufacturing a laminated core according to a fourthembodiment of the present invention, and FIG. 7(C) is a plan viewshowing a laminated core manufactured by the method.

FIG. 8 is an explanatory diagram showing a method of manufacturing alaminated core according to a conventional example.

FIG. 9 is an explanatory diagram showing a method of manufacturing alaminated core according to a conventional example.

DESCRIPTION OF EMBODIMENTS

As shown in FIG. 1, in a method of manufacturing a laminated coreaccording to a first embodiment of the present invention, a laminatedcore body 14 is placed between an upper die 10, which is an example of amolding die, and a lower die 11, which is an example of a retaining die.The laminated core body 14 has a plurality of pairs of magnet insertionholes 12 and 13 vertically penetrating therethrough (see FIG. 3(B)) in aradially-outward region thereof. The laminated core body 14 is placedwith a magnet piece (unexcited permanent magnet) 15 inserted in each ofthe magnet insertion holes 12 and 13. Further, a molding resin 19 isfilled via a guide member 18 into the magnet insertion holes 12 and 13from resin reservoir pots 16, which are examples of resin reservoirportions formed in the upper die 10, to fix the magnet pieces 15 in themagnet insertion holes 12 and 13. Here, a height of the magnet piece 15is equal to a height of the laminated core body 14 or smaller than theheight of the laminated core body 14 with a slight difference (0.1 to 2mm).

The laminated core body 14 includes a plurality of pairs (8 pairs inthis embodiment) of the paired magnet insertion holes 12 and 13 (whichform a group of the magnet insertion holes), and a through-hole 21 as alightening hole is formed in each radially-inward region between themagnet insertion holes 12 and 13, which are arranged in a chevron shapewhen viewed in plan. At a center of the laminated core body 14, a shafthole 22 is formed, and inside the shaft hole 22, projecting portions 23and 24 (see FIG. 3) are formed. The projecting portions 23 and 24 arerectangular when viewed in plan and are disposed opposite each other.The laminated core body 14 is formed by caulking and laminating coresheets 25, which are pressed from a magnetic metal sheet (e.g., siliconsteel plate) and have an identical shape.

As shown in FIG. 3(A), the upper die 10 includes the resin reservoirpots 16 having circular sections at the positions radially inward of thepaired magnet insertion holes 13 and 12 in a V-shape when viewed inplan. A liquefied molding resin (thermosetting resin) 19 filled insideeach of the resin reservoir pots 16 is extruded to the laminated corebody 14 by a plunger 27 moved up and down by an unillustrated cylinder.

The guide member 18 is made of one flat plate (e.g., stainless steelplate or steel plate) with a thickness, for example, of 0.2 to 3 mm. Theguide member 18 includes resin passages 31, which are bottomed groovesopened to the upper die 10. Upstream ends of the resin passages 31 areconnected to the resin reservoir pots 16, and downstream ends thereofare connected to gates 30, which are through-holes each formed in aradially-inward region of the magnet insertion holes 12 and 13 (shown indotted lines). A depth of the resin passage 31 is 30 to 70% of athickness of the guide member 18. The gates 30 formed at the downstreamends of the resin passages 31 are rectangular holes, and are provided atcenters of the radially-inward regions of the magnet insertion holes 12and 13 below the resin passages 31. Here, the gates 30 are not limitedto be rectangular holes, but may be circular holes, triangular holes,etc.

A length of a long side of the gate 30 is 0.3-fold to 0.7-fold of alength of a long side of the magnet insertion holes 12 and 13. Also, alength of a short side of the gate 30 is 0.3-fold to 0.7-fold of alength of a short side of the magnet insertion holes 12 and 13.

A diameter of the guide member 18 is larger than a diameter of thelaminated core body 14 by 1 to 10%. Inside the guide member 18, a shafthole 32, which has a diameter identical to a diameter of a shaft hole 22of the laminated core body 14, is provided. Inside the shaft hole 32,projecting portions 33 and 34, which are identical to projectingportions 23 and 24 provided inside the shaft hole 22, are provided.

In this embodiment, the laminated core body 14 is mounted on a carrierfixture 36, and positioned and held between the lower die 11 and theupper die 10.

As shown in FIG. 2, the carrier fixture 36 includes a mounting portion37 and a guide shaft 38 disposed at a center thereof. A length of theguide shaft 38 is longer than a height of the laminated core body 14,and a chamfer 39 is formed at an upper end of the guide shaft 38. Theupper die 10 includes a hole 40 into which the guide shaft 38 isinserted. At both sides in a radial direction of the guide shaft 38, keyslots 41 and 42 are provided, into which the projecting portions 23, 24,33, and 34 are inserted in close contact therewith. Alternatively, keyslots may be formed in an outer circumference of a shaft hole of alaminated core, and projecting portions, which are inserted into the keyslots, may be provided on a guide shaft.

Hereinafter, a method of manufacturing a laminated core using a resinsealing apparatus constituted as described above will be described.

After the guide member 18 is stacked on the laminated core body 14preheated and mounted on the carrier fixture 36, they are togetherplaced between the upper die 10 and the lower die 11. The laminated corebody 14 and the guide member 18 are positioned by lowering the upper die10 to insert the guide shaft 38 of the carrier fixture 36 into the hole40 of the upper die 10.

Here, the plungers 27 are pushed down by the unillustrated cylinders toextrude the liquefied molding resin 19 in the resin reservoir pots 16downward. The molding resin 19 is filled in each of the magnet insertionholes 12 and 13 from the resin passage 31 via the gate 30. Since thegates 30 are provided in a way that they overlap radially-inward regionsof the magnet insertion holes 12 and 13, the magnet pieces 15 are pushedto radially-outward regions of the magnet insertion holes 12 and 13.

Since the molding resin 19 is a thermosetting resin, it is heated andcured by the preheated laminated core body 14.

The upper die 10 is then lifted and the guide member 18 is removed fromthe laminated core body 14, and the cured molding resin 19 is broken ator near the gates 30. This procedure can be performed on the lower die11. Alternatively, this procedure can be performed after the carrierfixture 36 is moved to another place.

Next, by referring to FIGS. 4(A) and 4(B), a method of manufacturing alaminated core according to a second embodiment of the present inventionwill be described only for parts different from the method according tothe first embodiment of the present invention. The upper die 10, thelower die 11, and the carrier fixture 36, which are the same as thosedescribed in the first embodiment of the present invention, are used. Ina laminated core body 44, magnet insertion holes 45 are provided inaddition to the magnet insertion holes 12 and 13, forming eight groupsof the magnet insertion holes. Therefore, in a guide member 47 to bemounted on the laminated core body 44, resin passages 48 and gates 49corresponding to the magnet insertion holes 45 are provided.

Detailed descriptions of procedures for the method of manufacturing thelaminated core according to the second embodiment are omitted becausethe procedures are the same as those of the method of manufacturing thelaminated core according to the first embodiment.

In these embodiments, the resin is filled from one resin reservoir potto two or three magnet insertion holes. Further, the present inventionis applicable to a case where the resin is filled from one resinreservoir pot to one magnet insertion hole or to four or more magnetinsertion holes.

Next, by referring to FIGS. 5 and 6, a method of manufacturing alaminated core according to a third embodiment of the present inventionwill be described. Hereunder, detailed descriptions of an upper die anda lower die will be omitted because they are the same as those used inthe method of manufacturing the laminated core according to the firstembodiment. Also, although a carrier fixture for a laminated core bodyis omitted (not used) in the third embodiment, it is preferable to usethe carrier fixture as described in the first embodiment. In addition,elements which are the same as those in the above-mentioned embodimentsare numbered accordingly, and repetitive descriptions of the elementswill be omitted (likewise in a fourth embodiment of the presentinvention).

As shown in FIG. 5 and FIGS. 6(A) to 6(C), the laminated core body 14with a guide member 51 mounted thereon is placed between the upper die10 and the lower die 11. In the laminated core body 14, the magnetinsertion holes 12 and 13 are provided as described above. In thisembodiment, the guide member 51 includes two annular flat plates 52 and53 made of stainless-steel, and a thickness of each of the flat plates52 and 53 is, for example, 0.2 to 2 mm. The flat plate 52 adjoining theresin reservoir pots 16 includes resin passages 55, each formed from theresin reservoir pot 16 to a gate 54 on a downstream side of the resinpassage 55. The flat plate 53 adjoining the laminated core body 14includes the gates 54, through which the resin is filled into the magnetinsertion holes 12 and 13 formed in the laminated core body 14.

The resin passage 55 is formed by vertically penetrating through theflat plate 52, and the gate 54 is formed by vertically penetrating (as athrough-hole) through the flat plate 53. The gate 54 is provided at aradially-inward center of each of the magnet insertion holes 12 and 13when viewed in plan. The upstream side of the resin passage 55 isconnected to the resin reservoir pot 16, and the downstream side thereofis connected to the gate 54.

Accordingly, the two flat plates 52 and 53 are integral with each other,working in the same way as the guide member 18 provided with the resinpassages 31 and the gates 30 in the first embodiment. Here, diameters ofthe flat plates 52 and 53 are larger than a diameter of the laminatedcore body 14, thus the flat plates 52 and 53 can be removed easily.

The guide member 51 is used in the same way as described in the firstembodiment. By removing the guide member 51, which means removing theflat plates 52 and 53 simultaneously, and further by separating the flatplates 52 and 53, the molding resin remained in the resin passage 55 canbe easily removed.

In addition, it is preferable to use the carrier fixture 36 (not shownin FIG. 5), but if a positioning means (e.g., recessed portion andprojecting portion) to position the guide member 51 and the laminatedcore body 14 is provided, the carrier fixture can be omitted. In FIGS.6(A) and 6(B), reference numerals 57 and 58 denote projecting portionsand reference numerals 59 and 60 denote shaft holes.

Next, by referring to FIGS. 7(A) to 7(C), a method of manufacturing alaminated core according to a fourth embodiment of the present inventionwill be described. In this embodiment, the laminated core body 44 usedin the second embodiment of the present invention is used. In the fourthembodiment of the present invention, two flat plates 63 and 64 are usedto form a guide member 62. In the flat plate 63, the resin passages 55and 66 are provided. The resin passages 55 and 66 are connected from theresin reservoir pots provided in the upper die to the gates 54 and 65 ondownstream sides. In the flat plate 64, the gates 54 and 65 areprovided. The gates 54 and 65 are located at radially-inward centers ofthe magnet insertion holes 12, 13, and 45 of the laminated core body 44.

The predetermined magnet pieces 15 are inserted in the magnet insertionholes 12, 13, and 45, and the guide member 62 is positioned and mountedon the laminated core body 44. The laminated core body 44 and the guidemember 62 are then held together by the upper die and the lower die.After that, the molding resin is filled from the resin reservoir pots tothe magnet insertion holes 12, 13, and 45 via the resin passages 55 and66 and the gates 54 and 65. Accordingly, the magnet pieces 15 are fixedin the magnet insertion holes 12, 13, and 45. When the guide member 62is removed, the molding resin is removed without remaining on thelaminated core body 44.

As described above, by manufacturing the guide members 18, 47, 51, and62 in accordance with a shape of the laminated core body, it is notnecessary to modify a shape of the molding die, thus manufacturing costfor the molding die can be reduced.

In addition, since the guide members 18, 47, 51, and 62 are replaceablein accordance with the shape of the laminated core body, the device(resin sealing apparatus) can be easily changed even when the shape ofthe laminated core body is changed.

Furthermore, if the guide member includes two or more flat plates, itmay be sufficient that only one of the flat plates is replaced inaccordance with the shape of the laminated core body.

In the above embodiments, the resin reservoir pots are provided in theupper die, but the resin reservoir pots can also be provided in thelower die to fill the molding resin from below to each of the magnetinsertion holes. Moreover, although specific dimensions are shown indescriptions of the above embodiments, it is possible to change thevalues of the specific dimensions without departing from the scope ofthe present invention.

Furthermore, although the method of manufacturing the laminated coreaccording to the present invention is described by referring to thefirst to fourth embodiments above, a part or all of the aboveembodiments can be combined to constitute the present invention.

REFERENCE SIGNS LIST

10: upper die, 11: lower die, 12, 13: magnet insertion hole, 14:laminated core body, 15: magnet piece, 16: resin reservoir pot, 18:guide member, 19: molding resin, 21: through-hole, 22: shaft hole, 23,24: projecting portion, 25: core sheet, 27: plunger, 30: gate, 31: resinpassage, 32: shaft hole, 33, 34: projecting portion, 36: carrierfixture, 37: mounting portion, 38: guide shaft, 39: chamfer, 40: hole,41, 42: key slot, 44: laminated core body, 45: magnet insertion hole,47: guide member, 48: resin passage, 49: gate, 51: guide member, 52, 53:flat plate, 54: gate, 55: resin passage, 57: projecting portion, 58:projecting portion, 59: shaft hole, 60: shaft hole, 62: guide member,63, 64: flat plate, 65: gate, 66: resin passage

1-12. (canceled)
 13. A method of manufacturing a laminated core, thelaminated core formed by placing a laminated core body having magnetpieces inserted in magnet insertion holes of the laminated core bodybetween a molding die and a retaining die, filling a molding resin fromresin reservoir portions of the molding die to the magnet insertionholes, and thereby fixing the magnet pieces in the magnet insertionholes, the method comprising: placing a guide member between the moldingdie and the laminated core body, the guide member comprising: a)groove-type resin passages provided from the resin reservoir portions tothe magnet insertion holes; and b) gates on downstream sides of theresin passages, the gates being through holes, the gates connected tothe magnet insertion holes.
 14. The method as defined in claim 13,wherein the guide member is made of one flat plate, the resin passagecomprises a groove opened to the molding die, and the gate is athrough-hole provided at an end of the resin passage.
 15. The method asdefined in claim 13, wherein the guide member comprises at least twoflat plates, the resin passage is formed by penetrating through one ofthe flat plates adjoining the molding die, the gate is formed in anotherflat plate adjoining the laminated core body, and the gate is athrough-hole connected to a downstream side of the resin passage. 16.The method as defined in claim 13, wherein the gate is smaller than themagnet insertion hole when viewed in plan, and overlaps with the magnetinsertion hole on a radially-inward side of the magnet insertion hole.17. The method as defined in claim 14, wherein the gate is smaller thanthe magnet insertion hole when viewed in plan, and overlaps with themagnet insertion hole on a radially-inward side of the magnet insertionhole.
 18. The method as defined in claim 15, wherein the gate is smallerthan the magnet insertion hole when viewed in plan, and overlaps withthe magnet insertion hole on a radially-inward side of the magnetinsertion hole.
 19. The method as defined in claim 13, wherein themolding die comprises a plurality of the resin reservoir portions, andthe molding resin is supplied from the resin reservoir portions to aplurality of groups of the magnet insertion holes formed in thelaminated core body.
 20. The method as defined in claim 14, wherein themolding die comprises a plurality of the resin reservoir portions, andthe molding resin is supplied from the resin reservoir portions to aplurality of groups of the magnet insertion holes formed in thelaminated core body.
 21. The method as defined in claim 15, wherein themolding die comprises a plurality of the resin reservoir portions, andthe molding resin is supplied from the resin reservoir portions to aplurality of groups of the magnet insertion holes formed in thelaminated core body.
 22. The method as defined in one of claim 13,wherein a diameter of the guide member is larger than a diameter of thelaminated core body.
 23. The method as defined in one of claim 14,wherein a diameter of the guide member is larger than a diameter of thelaminated core body.
 24. The method as defined in one of claim 15,wherein a diameter of the guide member is larger than a diameter of thelaminated core body.